At present devices already exist that enable turning the pages of a document automatically, for example, in order to photocopy or digitize it.
Such a device is described, for example, in the U.S. Pat. No. 4,943,502. This device has two transparent trays on which the document is set in such a way that the pages of the document are turned downward. Between the trays is a slot below which are two adjacent cylinders, one of which has suction holes. The document is held by a movable template so that it can be moved with respect to the trays. In order to turn a page, the document is pushed by means of the template in the direction of the slot. A page of this document is sucked by the cylinders provided with suction holes. This page turns between the two cylinders and penetrates into a housing situated below the cylinders. When the document continues to advance under the effect of the movement of the template, the page is withdrawn from the housing and placed on the side of the already turned pages.
This device has a certain number of disadvantages. Given that the sheets execute a trajectory around the suction cylinder, the device cannot be used for certain types of paper. In particular, it is not possible to turn board-bound pages. Moreover, a document must necessarily be open before beginning to turn the pages. Furthermore, if it contains a board-bound inset, the machine becomes immobilized. Because of the face downward position of the document and the curvature to which the pages are subjected, they can be damaged or destroyed, particularly when the pages which are presented are pressed by the weight of the document against the holding device. This device is therefore not suitable for old and/or valuable documents. Furthermore, given that the template must be suited to the dimensions of the document, the device is not very practical for dealing with documents with different formats. With the document turned downward, it is necessary to integrate in the support structure an apparatus which can do photocopies or digitization. This means that it is necessary to choose a given type of apparatus and that it is practically impossible later to change it without designing a completely new machine.
Another device, intended particularly for handicapped people, is also known through the French Patent FR 2 713 149. This device has two trays, mounted independently from one another using elastic means, on which the document is set. Each tray can apply the pages of a document against at least one finger. These fingers are retractable. The page turning component is a roller provided with a pressing device and has some means of lateral translation in order to go from one edge of the document to the other. The main disadvantage of this execution is connected with the fact that since the trays for holding the document are independent but connected by elastic means, it is very difficult to manage the force applied to the document between the trays and the retractable fingers.
The device to which the U.S. Pat. No. 4,691,909 relates has two movable trays which are inclined toward one another and on which the document is set. The page is held open by a device with rods that rest on the visible pages. A roller capable of turning is brought into forced contact against the document. It turns in one direction and can take several sheets. It brings these sheets against a squeezing member and then turns in the reverse direction in order to eliminate the extra pages. In a rocking movement, the roller and the squeezing member send the turned page onto the other side. This page falls back by its own weight, and it is regained by the rod device.
In these last two devices, the page turning component turns the pages and carries them along by friction on their surface, which can damage sensitive pages or even erase the contents at the point of friction. The page separation process requires the page carried along to be flexible so that it can become convex when it is pushed from its end towards its bound part. The effectiveness of the separation of the pages by friction and by relative movement is greatly dependent on the type of paper and on the surface condition of the paper. This type of page separation has difficulty guaranteeing that only a single page is turned at a time. Furthermore, the page holding fingers or rods have support points concentrated over a small area, which can mark or damage the document. These objects are also a problem with regard to the visibility of the pages.
U.S. Pat. No. 5,471,277 relates to a device for reading a document, provided with a page turner arranged for installation on a photocopier, a fax, or the like, which has a support table for the document and a page turner in the form of a belt made of dielectric material associated with an electrical field generator in order to attract the page electrostatically.
GB 2 207 423 relates to an apparatus for turning the pages of a document, which has a table on which the document is set open, some means for applying a frictional force to the upper page in order to raise it and allow air to insert itself between this page and the next one. The insertion of a horizontally movable transparent plate in the space thus created turns the raised page.